Study type: Medical/biological study (experimental study)

The effect of melatonin on body mass and behaviour of rats during an exposure to microwave radiation from mobile phone med./bio.

Published in: Bratisl Lek Listy 2012; 113 (5): 265-269

Aim of study (acc. to author)

To determine body mass and behaviour changes in rats after a chronic microwave exposure with and without melatonin treatment.

Background/further details

Rats were divided into 4 groups (n= 10 per group): 1.) control group treated with 0.9 % saline, 2.) treated with melatonin (2 mg/kg per day), 3.) exposed and 4.) exposed + melatonin (2 mg/kg per day).



Exposure Parameters
Exposure 1: 900 MHz
Modulation type: CW
Exposure duration: continuous for 4 h/day on 60 days

General information

Rats were divided into the following four groups: i) control group ii) treated with melatonin (2 mg/kg per day) iii) microwave exposure iv) melatonin treatment + microwave exposure

Exposure 1

Main characteristics
Frequency 900 MHz
Exposure duration continuous for 4 h/day on 60 days
Modulation type CW
Exposure setup
Exposure source
Setup eight rats placed in a plastic cage during exposure; mobile phone positioned in the cage's center in a special compartment with the antenna pointing downwards; cage placed on absorbing rubber material with a wooden surface
Measurand Value Type Method Mass Remarks
electric field strength 9.88 V/m minimum measured - -
electric field strength 18.35 V/m maximum measured - -
magnetic flux density 4.68 µT minimum measured - -
magnetic flux density 8.69 µT maximum measured - -
SAR 0.043 W/kg minimum calculated whole body -
SAR 0.135 W/kg maximum calculated whole body -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Significant body mass reduction was noted in exposed animals when compared to the control group after 20, 40 and 60 days. An administration of melatonin (group 2) caused a significant increase in body weight after 20 days in comparison to the control group. Exposed rats, treated with melatonin, showed a significant increase in body mass after 20 days when compared to the exposed rats.
After 10 days of exposure, changes in the behavior of the rats occurred, which became more intensive with a maximum after 60 days: In both exposure groups, a reduced locomotor activity was noticed in comparison to the unexposed groups, but no differences between the exposure group with melatonin administration and the exposure group without melatonin administration occurred. The exposed animals, not treated with melatonin, showed more anxiety and agitation (more grooming, moving away from the source of exposure) and less exploratory behavior (less rearing) than the unexposed groups. The exposed animals treated with melatonin, showed less stress compared to the exposed rats without melatonin administration.
The authors conclude that microwave exposure could cause a body mass decrease and anxiety related behavior. However, treatment with melatonin could cause a reverse of those effects.

Study character:

Study funded by

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